\Header{grid.circle}{Draw a Circle}
\keyword{dplot}{grid.circle}
\begin{Description}\relax
This function draws a circle.\end{Description}
\begin{Usage}
\begin{verbatim}
grid.circle(x=0.5, y=0.5, r=0.5, default.units="npc",
            gp=gpar(), draw=TRUE, vp=NULL)
\end{verbatim}
\end{Usage}
\begin{Arguments}
\begin{ldescription}
\item[\code{x}] A numeric vector or unit object specifying x-locations.
\item[\code{y}] A numeric vector or unit object specifying y-locations.
\item[\code{r}] A numeric vector or unit object specifying radii.
\item[\code{default.units}] A string indicating the default units to use
if \code{x}, \code{y}, \code{width}, or \code{height}
are only given as numeric vectors.
\item[\code{gp}] An object of class \code{gpar}, typically the output
from a call to the function \code{gpar}.  This is basically
a list of graphical parameter settings.
\item[\code{draw}] A logical value indicating whether graphics output
should be produced.
\item[\code{vp}] A Grid viewport object (or NULL).
\end{ldescription}
\end{Arguments}
\begin{Details}\relax
The radius may be given in any
units;  if the units are \emph{relative} (e.g., \code{"npc"} or
\code{"native"}) then the radius will be different depending on
whether it is interpreted as a width or as a height.  In such cases,
the smaller of these two values will be the result.  To see the
effect, type \code{grid.circle()} and adjust the size of the window.

The \code{"grob"} object contains an object of class \code{"circle"}.\end{Details}
\begin{Value}
An object of class \code{"grob"}.\end{Value}
\begin{Author}\relax
Paul Murrell\end{Author}
\begin{SeeAlso}\relax
\link{Grid},
\code{\Link{viewport}}\end{SeeAlso}

